In the U.S.—

In Canada—

Another commonly used name isN-acetylcysteine.

• Mucolytic; diagnostic aid (bronchial studies)

Acetylcysteine (a-se-teel-SIS-teen ) is a mucolytic (medicine that destroys or dissolves mucus). It is usually given by inhalation but may be given in other ways in a hospital.

Acetylcysteine is used for certain lung conditions when increased amounts of mucus make breathing difficult. Acetylcysteine liquefies (thins) or dissolves mucus so that it may be coughed up. Sometimes the mucus may have to be removed by suction.

This medicine is available only with your doctor's prescription, in the following dosage form:

Inhalation
• Solution (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For acetylcysteine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to acetylcysteine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Acetylcysteine has not been studied in pregnant women. However, acetylcysteine has not been shown to cause birth defects or other problems in animal studies when given in doses larger than the recommended human dose.

Breast-feeding—It is not known whether acetylcysteine passes into the breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor.

Children—Although there is no specific information comparing use of acetylcysteine in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of acetylcysteine in the elderly with use in other age groups.

• Asthma—Acetylcysteine may make the condition worse

• Decreased ability to cough—The mucus may have to be removed by suctioning

Use acetylcysteine only as directed. Do not use more of it and do not use it more often than your doctor ordered. To do so may increase the chance of side effects.

If you are using this medicine at home, make sure you understand exactly how to use it. If you have any questions about this, check with your doctor.

After using acetylcysteine, try to cough up the loosened or thinned mucus. If this does not work, it may have to be suctioned out. This will prevent too much mucus from building up in the lungs. If you have any questions about this, check with your doctor.

Dosing—

The dose of acetylcysteine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of acetylcysteine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of solution that you use depends on the strength of the medicine and the method of inhalation used. Also, the number of doses you use each day, the time allowed between doses, and the length of time you use the medicine depend on the medical problem for which you are using acetylcysteine.

• For inhalation dosage form (solution):
  • To thin or dissolve mucus in lung diseases:
    • Adults and children—
      • 3 to 5 milliliters (mL) of a 20% solution or 6 to 10 mL of a 10% solution used in a nebulizer three or four times a day. The medicine is inhaled through a face mask, mouthpiece, or tracheostomy.
      • The 10 or 20% solution may be used for inhalation as a heavy mist in a tent or croupette.
      • Sometimes the 10 or 20% solution is placed directly into the trachea or through a catheter into the trachea for certain conditions.
  • For use in tests to diagnose lung problems:
    • Adults and children—1 to 2 mL of a 20% solution or 2 to 4 mL of a 10% solution used for inhalation or placed directly into the trachea two or three times before the test.

Missed dose—

If you miss a dose of this medicine, use it as soon as possible. Then use any remaining doses for that day at regularly spaced intervals.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Before the container is opened, store it away from heat and direct light.
• After the container is opened, store it in the refrigerator. However, keep the medicine from freezing. The opened container should be discarded after 4 days.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

If your condition does not improve or if it becomes worse, check with your doctor.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Less common
  • Wheezing, tightness in chest, or difficulty in breathing (especially in asthma patients) 
  
  

• Rare
  • Skin rash or other irritation 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• Less common
  • Clammy skin;  fever;  increase in amount of mucus in lungs;  irritation or soreness of mouth, throat, or lungs;  nausea or vomiting;  runny nose 
  
  

• The mask may leave a stickiness on your face. This can be removed with water.

When you use acetylcysteine, you may notice that the medicine has an unpleasant odor at first. However, this smell will go away soon after you use the medicine.

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.